Trailer active back-up assist with object avoidance

ABSTRACT

A trailer back-up assist apparatus comprises an obstacle sensing system operable to output information characterizing proximity of a object adjacent to a vehicle-trailer combination while the vehicle-trailer combination is being backed toward a targeted location and a trailer back-up assist system correction apparatus coupled to the obstacle sensing system. The trailer back-up assist system uses the information characterizing proximity of the object to determine if a path of the vehicle-trailer combination needs to be altered to limit a potential of the vehicle-trailer combination colliding with the object and implements a path correction action to alter the path of travel of the vehicle-trailer combination to reduce the potential for the vehicle-trailer combination colliding with the object.

FIELD OF THE DISCLOSURE

The disclosures made herein relate generally to driver assist and activesafety technologies in vehicles and, more particularly, to implementingobject avoidance integrally with trailer back-up assist.

BACKGROUND

It is well known that backing up a vehicle with a trailer attached is adifficult task for many drivers. This is particularly true for driverswho are untrained at backing with trailers such as, for example, thosewho drive with an attached trailer on an infrequent basis (e.g., haverented a trailer, use a personal trailer on an infrequent basis, etc).One reason for such difficulty is that backing a vehicle with anattached trailer requires counter-steering that is opposite to normalsteering when backing the vehicle without a trailer attached and/orrequires braking to stabilize the vehicle-trailer combination before ajack-knife condition occurs. Another reason for such difficulty is thatsmall errors in steering while backing a vehicle with an attachedtrailer are amplified, thereby causing the trailer to depart from adesired path. Still another reason is that there are often objectsand/or structures present that limit available space through which thetrailer is to be backed.

To assist the driver in steering a vehicle with trailer attached, atrailer back-up assist system needs to know the driver's intention. Onecommon assumption with known trailer back-up assist systems is that adriver of a vehicle with an attached trailer wants to back up straightand the system either implicitly or explicitly assumes a zero curvaturepath for the vehicle-trailer combination. Unfortunately, most ofreal-world use cases of backing a trailer involve a curved path and,thus, assuming a path of zero curvature would significantly limitusefulness of the system. Some known systems assume that a path is knownfrom a map or path planner. To this end, some known trailer back-upassist systems operate under a requirement that a trailer back-up pathis known before backing of the trailer commences such as, for example,from a map or a path planning algorithm. Undesirably, suchimplementations of the trailer back-up assist systems are known to havea relatively complex Human Machine Interface (HMI) to specify the path,obstacles and/or goal of the back-up maneuver. Furthermore, such systemsalso require some way to determine how well the desired path is beingfollowed and to know when the desired goal, or stopping point andorientation, has been met, using approaches such as cameras, inertialnavigation, or high precision GPS. These requirements lead to arelatively complex and costly system.

As previously mentioned, one reason backing a trailer can prove to bedifficult is the need to control the vehicle in a manner that limits thepotential for a jack-knife condition to occur. A trailer has attained ajack-knife condition when a hitch angle cannot be reduced (i.e., madeless acute) by application of a maximum steering input for the vehiclesuch as, for example, by moving steered front wheels of the vehicle to amaximum steered angle at a maximum rate of steering angle change. In thecase of the jack-knife angle being achieved, the vehicle must be pulledforward to relieve the hitch angle in order to eliminate the jack-knifecondition and, thus, allow the hitch angle to be controlled viamanipulation of the steered wheels of the vehicle. However, in additionto the jack-knife condition creating the inconvenient situation wherethe vehicle must be pulled forward, it can also lead to damage to thevehicle and/or trailer if certain operating conditions of the vehiclerelating to its speed, engine torque, acceleration, and the like are notdetected and counteracted. For example, if the vehicle is travelling ata suitably high speed and/or subjected to a suitably high longitudinalacceleration when the jack-knife condition is achieved, the relativemovement of the vehicle with respect to the trailer can lead to contactbetween the vehicle and trailer thereby damaging the trailer and/or thevehicle.

As also previously mentioned, another reason backing a trailer can proveto be difficult is that there are often objects and/or structurespresent that limit available space through which the trailer is to bebacked. A driver must therefore be concerned with not only backing thetrailer to an intended location but also with doing so in a mannerwhereby neither the vehicle nor the trailer collide with adjacentobjects and/or structures. Contributing to this challenge is that thepotential for the vehicle and trailer to attain a jack-knife conditionlimits maneuverability for navigating through such object withouthitting them.

Therefore, a solution for providing trailer back-up assist with objectavoidance would be beneficial, desirable and useful.

SUMMARY OF THE DISCLOSURE

Embodiments of the inventive subject matter are directed to assisting adriver with backing a trailer attached to a vehicle (i.e., thevehicle-trailer combination) in a manner that limits the potential forthe vehicle or trailer colliding with obstacles and/or structures (i.e.,adjacent objects) through which the trailer must be backed to attain atargeted (i.e., intended) location. To this end, embodiments of theinventive subject matter use the proximity of such adjacent objects asan input in an algorithm to correct the path of the vehicle and trailerto avoid colliding with such adjacent objects (i.e., path correctionfunctionality). In some implementations, the path correctionfunctionality can be applied in response to a driver of the vehicleguiding the vehicle through use of a Human Machine Interface (HMI). Inother implementations, the path correction functionality is performedautomatically in conjunction with controlling a path of travel of thevehicle using a variety of its electromechanical systems. The pathcorrection functionality can be implemented in a manner that limits thepotential for a jack-knife condition being attained between the vehicleand the trailer such as by detecting an impending jack-knife condition(i.e., a jack-knife enabling condition) and correspondingly implementinga jack-knife counter-measure for alleviating the impending jack-knifecondition. Optionally, in some embodiments of the inventive subjectmatter, a warning (e.g., tactile, audible, visual and/or the like) canbe implemented in response to an impending and/or actual condition(e.g., a jack-knife condition) being detected that required the vehicleto be pulled forward and/or provide notice of the vehicle or trailerapproaching an adjacent object. Accordingly, embodiments of theinventive subject matter contribute to trailer back-up assistfunctionality being implemented in a manner that is relatively simple,effective, and safe.

In one embodiment of the inventive subject matter, a method forassisting a driver to back a vehicle-trailer combination comprises aplurality of operations. An operation is performed for determiningproximity of an object adjacent to the vehicle-trailer combination whilethe vehicle-trailer combination is being backed toward a targetedlocation. An operation is performed for determining that a path of thevehicle-trailer combination needs to be altered to limit a potential ofthe vehicle-trailer combination colliding with the object based on theproximity of the object to the vehicle-trailer combination. Thereafter,an operation is performed to implement a path correction action to alterthe path of travel of the vehicle-trailer combination to reduce thepotential for the vehicle-trailer combination colliding with theadjacent object. One or more one data processing devices access, frommemory coupled to the one or more data processing devices, instructionsfor causing the one or more data processing devices to carry out suchoperations.

In another embodiment of the inventive subject matter, a trailer back-upassist apparatus comprises an obstacle sensing system operable to outputinformation characterizing proximity of a object adjacent to avehicle-trailer combination while the vehicle-trailer combination isbeing backed toward a targeted location and a trailer back-up assistsystem correction apparatus coupled to the obstacle sensing system. Thetrailer back-up assist system uses the information characterizingproximity of the object to determine if a path of the vehicle-trailercombination needs to be altered for limiting a potential of thevehicle-trailer combination colliding with the object and implements apath correction action to alter the path of travel of thevehicle-trailer combination to reduce the potential for thevehicle-trailer combination colliding with the object.

In another embodiment of the inventive subject matter, an electroniccontroller system has a set of instructions tangibly embodied on anon-transitory processor-readable medium thereof. The set ofinstructions is accessible from the non-transitory processor-readablemedium by one or more data processing devices of the electroniccontroller system for being interpreted thereby. The set of instructionsis configured for causing the one or more one data processing devices tocarry out a plurality of operations. An operation is performed todetermine proximity of an object adjacent to the vehicle-trailercombination while the vehicle-trailer combination is being backed towarda targeted location. An operation is performed to determine that a pathof the vehicle-trailer combination needs to be altered to limit apotential of the vehicle-trailer combination colliding with the objectbased on the proximity of the object to the vehicle-trailer combination.Thereafter, an operation is performed to implement a path correctionaction to alter the path of travel of the vehicle-trailer combination toreduce the potential for the vehicle-trailer combination colliding withthe adjacent object.

These and other objects, embodiments, advantages and/or distinctions ofthe inventive subject matter will become readily apparent upon furtherreview of the following specification, associated drawings and appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram showing a vehicle configured for performingtrailer back-up assist functionality in accordance with an embodiment ofthe inventive subject matter.

FIG. 1BA is a diagrammatic view showing a vehicle-trailer combinationconfigured in accordance with an embodiment of the inventive subjectmatter.

FIG. 1C is a flow diagram showing a method for providing the trailerback-up assist functionality with object avoidance.

FIG. 2 is a diagrammatic view showing a preferred embodiment of thetrailer back-up steering input apparatus discussed in reference to FIG.1A.

FIG. 3 is a diagrammatic view showing an example of a trailer back-upsequence implemented using the trailer back-up steering input apparatusdiscussed in reference to FIG. 2.

FIG. 4 is a flow diagram showing a method for implementing trailerback-up assist functionality in accordance with an embodiment of theinventive subject matter.

FIG. 5 is a diagrammatic view showing a kinematic model configured forproviding information utilized in providing trailer back-up assistfunctionality in accordance with the inventive subject matter.

FIG. 6 is a graph showing an example of a trailer path curvaturefunction plot for a rotary-type trailer back-up steering input apparatusconfigured in accordance with the inventive subject matter.

FIG. 7 is a diagrammatic view showing a relationship between hitch angleand steered angle as it relates to determining a jack-knife angle for avehicle/trailer system.

FIG. 8 is a flow diagram showing a method for implementing jack-knifecountermeasures functionality in accordance with an embodiment of theinventive subject matter.

DETAILED DESCRIPTION OF THE DRAWING FIGURES

The inventive subject matter is directed to providing trailer back-upassist functionality that includes object avoidance. As mentioned above,a reason backing a trailer can prove to be difficult is that there areoften objects and/or structures present that limit available spacethrough which the trailer is to be backed. A driver must therefore beconcerned with not only backing the trailer to an intended location butalso with doing so in a manner whereby neither the vehicle nor thetrailer collide with adjacent objects and/or structures. Contributing tothis challenge is that the potential for the vehicle and trailer toattain a jack-knife condition limits maneuverability for navigatingthrough such objects without hitting them. Embodiments of the inventivesubject matter use the proximity of such adjacent objects as an input inan algorithm to correct the path of the vehicle and trailer to avoidcolliding with such adjacent objects (i.e., path correctionfunctionality).

Embodiments of the inventive subject matter use the proximity ofobstacle as an input in an algorithm to correct the path of the vehicleand trailer to avoid colliding with the obstacle. It is well known thatthere are a variety of sensor technologies and systems used on currentvehicles to detect the presence of and/or distance to objects adjacentto the vehicle. For example, ultrasonic sensors and/or cameras are usedin Active Park Assist to detect curbs, walls, and vehicles and radar isused to warn drivers of objects in and around blind spots of thevehicle. Camera, ultrasonic sensors, and radar are examples of devicesconfigured for capturing information characterizing proximity of anobject (i.e., proximity information capturing device). To this end,embodiments of the inventive subject matter can utilize existingproximity information capturing device on the vehicle and/or useproximity information capturing device that are on the trailer (e.g., anaccessory item mounted on the trailer).

As discussed below in greater detail, in certain embodiments of theinventive subject matter, curvature of a path of travel of the trailer(i.e., trailer path curvature control) can be controlled by allowing adriver of the vehicle to specify a desired path of the trailer byinputting a desired trailer path curvature as the back-up maneuver ofthe vehicle and trailer progresses. Although a control knob, a set ofvirtual buttons, or a touch screen can each be implemented for enablingtrailer path curvature control, the inventive subject matter is notunnecessarily limited to any particular configuration of interfacethrough which a desired trailer path curvature is inputted. Furthermore,in the case where a steering wheel can be mechanically decoupled fromsteered wheels of the vehicle, the steering wheel can also be used as aninterface through which a desired trailer path curvature is inputted. Aswill be discussed herein in greater detail, kinematical information of asystem defined by the vehicle and the trailer are used to calculate arelationship (i.e., kinematics) between the trailer's curvature and thesteering angle of the vehicle for determining steering angle changes ofthe vehicle for achieving the specified trailer path. Steering commandscorresponding to the steering angle changes are used for controlling asteering system of the vehicle (e.g., electric power assisted steering(EPAS) system) of the vehicle for implementing steering angle changes ofsteered wheels of the vehicle to achieve (e.g., to approximate) thespecified path of travel of the trailer. Furthermore, as will bediscussed below, trailer back-up assist functionality in accordance withthe inventive subject matter can include one or more countermeasuresbeing implemented to limit the potential of a jack-knife condition beingattained between a vehicle and a trailer being towed by the vehicle.

Referring to FIG. 1A, an embodiment of a vehicle 100 configured forperforming trailer back-up assist functionality in accordance with theinventive subject matter is shown. A trailer back-up assist system 105of the vehicle 100 controls the curvature of path of travel of thetrailer 110 that is attached to the vehicle 100. Such control isaccomplished through interaction of a power assisted steering system 115of the vehicle 100 and the trailer back-up assist system 105. Duringoperation of the trailer back-up assist system 105 while the vehicle 100is being reversed, a driver of the vehicle 100 is sometimes limited inthe manner in which he/she can make steering inputs via a steering wheelof the vehicle 100. This is because in certain vehicles the trailerback-up assist system 105 is in control of the power assisted steeringsystem 115 and the power assisted steering system 115 is directlycoupled to the steering wheel (i.e., the steering wheel of the vehicle100 moves in concert with steered wheels of the vehicle 100). As isdiscussed below in greater detail, a human machine interface (HMI) ofthe back-up assist system 105 is used for commanding changes incurvature of a path of the trailer 110 such as a knob, therebydecoupling such commands from being made at the steering wheel of thevehicle 100. However, some vehicles configured to provide trailerback-up assist functionality in accordance with the inventive subjectmatter will have the capability to selectively decouple steeringmovement from movement of steerable wheels of the vehicle, therebyallowing the steering wheel to be used for commanding changes incurvature of a path of a trailer during such trailer back-up assist.

The trailer back-up assist system 105 includes a trailer back-up assistcontrol module 120, a trailer back-up steering input apparatus 125, anda hitch angle detecting apparatus 130. The trailer back-up assistcontrol module 120 is connected to the trailer back-up steering inputapparatus 125 and the hitch angle detecting apparatus 130 for allowingcommunication of information there between. It is disclosed herein thatthe trailer back-up steering input apparatus can be coupled to thetrailer back-up assist control module 120 in a wired or wireless manner.The trailer back-up assist system control module 120 is attached to apower-steering assist control module 135 of the power-steering assistsystem 115 for allowing information to be communicated therebetween. Asteering angle detecting apparatus 140 of the power-steering assistsystem 115 is connected to the power-steering assist control module 125for providing information thereto. The trailer back-up assist system isalso attached to a brake system control module 145, a powertrain controlmodule 150, and an object detection module 151 for allowingcommunication of information therebetween. Jointly, the trailer back-upassist system 105, the power-steering assist system 115, the brakesystem control module 145, the powertrain control module 150 define atrailer back-up assist architecture configured in accordance with anembodiment of the inventive subject matter.

The trailer back-up assist control module 120 is configured forimplementing logic (i.e., instructions) for receiving information fromthe trailer back-up steering input apparatus 125, the hitch angledetecting apparatus 130, the power-steering assist control module 135,the brake system control module 145, and the powertrain control module150. The trailer back-up assist control module 120 (e.g., a trailercurvature algorithm thereof) generates vehicle steering information as afunction of all or a portion of the information received from thetrailer back-up steering input apparatus 125, the hitch angle detectingapparatus 130, the power-steering assist control module 135, the brakesystem control module 145, and the powertrain control module 150.Thereafter, the vehicle steering information is provided to thepower-steering assist control module 135 for affecting steering of thevehicle 100 by the power-steering assist system 115 to achieve acommanded path of travel for the trailer 110.

The trailer back-up steering input apparatus 125 provides the trailerback-up assist control module 120 with information defining thecommanded path of travel of the trailer 110 to the trailer back-upassist control module 120 (i.e., trailer steering information). Thetrailer steering information can include information relating to acommanded change in the path of travel (e.g., a change in radius of pathcurvature) and information relating to an indication that the trailer isto travel along a path defined by a longitudinal centerline axis of thetrailer (i.e., along a substantially straight path of travel). As willbe discussed below in detail, the trailer back-up steering inputapparatus 125 preferably includes a rotational control input device forallowing a driver of the vehicle 100 to interface with the trailerback-up steering input apparatus 125 to command desired trailer steeringactions (e.g., commanding a desired change in radius of the path oftravel of the trailer and/or commanding that the trailer travel along asubstantially straight path of travel as defined by a longitudinalcenterline axis of the trailer). In a preferred embodiment, therotational control input device is a knob rotatable about a rotationalaxis extending through a top surface/face of the knob. In otherembodiments, the rotational control input device is a knob rotatableabout a rotational axis extending substantially parallel to a topsurface/face of the knob.

Some vehicles (e.g., those with active front steer) have apower-steering assist system configuration that allows a steering wheelto be decoupled from movement of the steered wheels of such a vehicle.Accordingly, the steering wheel can be rotated independent of the mannerin which the power-steering assist system of the vehicle controls thesteered wheels (e.g., as commanded by vehicle steering informationprovided by to a power-steering assist system control module from atrailer back-up assist system control module configured in accordancewith an embodiment of the inventive subject matter). As such, in thesetypes of vehicles where the steering wheel can be selectively decoupledfrom the steered wheels to allow independent operation thereof, trailersteering information of a trailer back-up assist system configured inaccordance with the inventive subject matter can be provided throughrotation of the steering wheel. Accordingly, it is disclosed herein thatin certain embodiments of the inventive subject matter, the steeringwheel is an embodiment of a rotational control input device in thecontext of the inventive subject matter. In such embodiments, thesteering wheel would be biased (e.g., by an apparatus that isselectively engagable/activatable) to an at-rest position betweenopposing rotational ranges of motion.

The hitch angle detecting apparatus 130, which operates in conjunctionwith a hitch angle detection component 155 of the trailer 110, providesthe trailer back-up assist control module 120 with information relatingto an angle between the vehicle 100 and the trailer 110 (i.e., hitchangle information). In a preferred embodiment, the hitch angle detectingapparatus 130 is a camera-based apparatus such as, for example, anexisting rear view camera of the vehicle 100 that images (i.e., visuallymonitors) a target (i.e., the hitch angle detection component 155)attached the trailer 110 as the trailer 110 is being backed by thevehicle 100. Preferably, but not necessarily, the hitch angle detectioncomponent 155 is a dedicated component (e.g., an item attachedto/integral with a surface of the trailer 110 for the express purpose ofbeing recognized by the hitch angle detecting apparatus 130).Alternatively, the hitch angle detecting apparatus 130 can be a devicethat is physically mounted on a hitch component of the vehicle 100and/or a mating hitch component of the trailer 110 for determining anangle between centerline longitudinal axes of the vehicle 100 and thetrailer 110. The hitch angle detecting apparatus 130 can be configuredfor detecting a jack-knife enabling condition and/or related information(e.g., when a hitch angle threshold has been met).

The power-steering assist control module 135 provides the trailerback-up assist control module 120 with information relating to arotational position (e.g., angle) of the steering wheel angle and/or arotational position (e.g., turning angle(s)) of steered wheels of thevehicle 100. In certain embodiments of the inventive subject matter, thetrailer back-up assist control module 120 can be an integrated componentof the power steering assist system 115. For example, the power-steeringassist control module 135 can include a trailer back-up assist algorithmfor generating vehicle steering information as a function of all or aportion of information received from the trailer back-up steering inputapparatus 125, the hitch angle detecting apparatus 130, thepower-steering assist control module 135, the brake system controlmodule 145, and the powertrain control module 150.

The brake system control module 145 provides the trailer back-up assistcontrol module 120 with information relating to vehicle speed. Suchvehicle speed information can be determined from individual wheel speedsas monitored by the brake system control module 145. In some instances,individual wheel speeds can also be used to determine a vehicle yawangle and/or yaw angle rate and such yaw angle and/or yaw angle rate canbe provided to the trailer back-up assist control module 120 for use indetermining the vehicle steering information. In certain embodiments,the trailer back-up assist control module 120 can provide vehiclebraking information to the brake system control module 145 for allowingthe trailer back-up assist control module 120 to control braking of thevehicle 100 during backing of the trailer 110. For example, using thetrailer back-up assist control module 120 to regulate speed of thevehicle 100 during backing of the trailer 110 can reduce the potentialfor unacceptable trailer back-up conditions. Examples of unacceptabletrailer back-up conditions include, but are not limited to, a vehicleoverspeed condition, trailer angle dynamic instability, a trailerjack-knife condition as defined by an angular displacement limitrelative to the vehicle 100 and the trailer 110, and the like. It isdisclosed herein that the back-up assist control module 120 can issue asignal corresponding to a notification (e.g., a warning) of an actual,impending, and/or anticipated unacceptable trailer back-up condition.

The powertrain control module 150 interacts with the trailer back-upassist control module for regulating speed and acceleration of thevehicle 100 during backing of the trailer 110. As mentioned above,regulation of the speed of the vehicle 100 is necessary to limit thepotential for unacceptable trailer back-up conditions such as, forexample, jack-knifing and trailer angle dynamic instability. Similar tohigh-speed considerations as they relate to unacceptable trailer back-upconditions, high acceleration can also lead to such unacceptable trailerback-up conditions.

The obstacle sensing system 151 captures, generates, and outputsinformation characterizing proximity of objects adjacent to the vehicle100. As shown in FIG. 1B, the obstacle sensing system 151 can include aplurality of proximity information capturing devices 153 that are eachmounted on the vehicle 100 of the vehicle-trailer combination 111 (i.e.,the vehicle 100 with the trailer 110 attached thereto). Examples of thevehicle-mounted proximity information capturing devices 153 include, butare not limited to one or more ultrasonic sensors, one or more cameras,and one or more radar transceivers. As shown in FIGS. 1A and 1B, thetrailer 110 can also include one or more trailer-mounted proximityinformation capturing devices 157 that can be coupled to the obstaclesensing system 151 or optionally to the trailer-back-up assist controlmodule 120. Examples of the trailer-mounted proximity informationcapturing devices 157 include, but are not limited to one or moreultrasonic sensors, one or more cameras, and one or more radartransceivers. Accordingly, the one or more vehicle-mounted proximityinformation capturing devices 153 enable proximity of objectsapproaching a rear portion of the vehicle 100 and a front portion of thetrailer 110 to be determined and the one or more trailer-mountedproximity information capturing devices 157 enable proximity of objectsapproaching a rear portion of the trailer 110 to be determined.

FIG. 1C shows an embodiment of a method 190 for providing trailerback-up assist functionality with object avoidance is shown. In oneembodiment, the trailer back-up assist system 105 and vehicle-trailercombination ill that are disclosed and discussed above are configuredfor carrying out the method 190 for providing trailer back-up assistfunctionality with object avoidance. The method 190 begins with anoperation 192 being performed to determine proximity of an objectadjacent to the vehicle-trailer combination 111. For example, duringbacking of the vehicle-trailer combination 111, information transmittedfrom proximity information capturing devices mounted on the vehicle 100and/or trailer 110 to the trailer back-up assist system 105 is used todetermine proximity of the vehicle 100 and/or trailer 110 to an adjacentobject.

After determining proximity of the object, an operation 194 is performedto determine if a path of the vehicle-trailer combination needs to bealtered (i.e., a vehicle-trailer path correction) for limiting apotential of the vehicle-trailer combination colliding with the object.Determination on the vehicle-trailer path correction is based onproximity of the vehicle-trailer combination 111 to the obstacle.Determination on the vehicle-trailer path correction can also be basedon one or more other systems of the vehicle 100 assessing a thresholdindicating that the vehicle-trailer combination 111 is approaching acollision condition with respect to the object (i.e., a collisionthreshold). Examples of the manner in which these other systems can beused for determining if the vehicle-trailer path correction is requiredinclude, but are not limited to, engine torque request dynamic transientbehavior and magnitudes being used to assess the collision threshold,longitudinal acceleration being used to assess the collision threshold,steering wheel angle rates and dynamic transient behavior being used inpredefined or calculated mappings to assess the collision threshold,drive input trailer curvature command transient behavior can be used ina predefined or calculated mappings using current hitch angle positionto assess the collision threshold, and hitch angle rate being be used ina predefined or calculated mapping to assess the collision threshold.These other systems can be associated with one or more of the followingfunctional mechanisms of the vehicle: electric power steering, activefront steer, four wheel steer, automatic braking, throttle control, andautomatic gear selection.

If it is determined that a vehicle-trailer path correction is notrequired, the method 100 continues to the operation 192 to determineproximity of an object adjacent to the vehicle-trailer combination Ill(e.g., the same and/or different object). If it is determined that avehicle-trailer path correction is required, an operation 196 isperformed for determining a suitable and appropriate action to correctthe path of the trailer-vehicle combination (i.e., path correctionaction) to mitigate the potential for collision with the object andthereafter an operation 198 is performed to implement the pathcorrection action. The path correction action can be implemented byguiding the driver entirely through a Human Machine Interface (HMI)and/or automatically controlling the vehicle using a variety ofelectromechanical systems thereof (e.g., systems associated withelectric power steering, active front steer, four wheel steer, automaticbraking, throttle control, and automatic gear selection).

Determination of the path correction action can be made on any number ofbases. For example, prioritisation can be given to object avoidance modethat has the highest probability of mitigating a collision and/or lowestinfluence on operation of the vehicle. Examples of object avoidancestrategies for implementing the path correction action include, but arenot limited to, speed control strategy, steering control strategy, andtrailer curvature control strategy. A speed control strategy can includea combination of throttle deactivation or limiting and automaticfriction or transmission braking may be used to reduce the speed of thevehicle to reduce collision probability when prescribed collisionavoidance criteria (e.g., a respective collision avoidance threshold)corresponding to avoiding collision with the object have been satisfied.A steering control strategy can include steering rates, steering angleslimits, relative road wheel angles and speeds and transitional controlinputs being reduced or limited in order to satisfy prescribed collisionavoidance criteria corresponding to avoiding collision with the object.A trailer curvature control strategy can include a trailer curvaturecontrol target (i.e., commanded value) being reduced in the trailerback-up assist system utilizing, for example, automated steering or HMIguidance, based on mappings using vehicle speed, acceleration, steeringrate and/or transitional steering wheel angle behavior to reduce thepotential for collision with the object. Accordingly, implementing thepath correction action can include issuing a path correction actioncommand for causing one or more object avoidance strategies to beinitiated.

In combination with or as a component of determining that the pathcorrection action is required and/or implementing the path correctionaction, a warning communication can be initiated. Examples of suchwarning communications include, but are not limited to, a visualwarning, an audible warning, and a tactile warning. A visual warning caninclude a display strategy utilizing a smart device of the driver of thevehicle (e.g., a cell phone or tablet) and/or one or more subsystems inthe vehicle (e.g., illuminated steering wheel/knob, illuminated cameradisplay, heads up display, illuminated mirrors text or schematicscreen). These visual warnings can include color, intensity, and blinkfrequencies to provide feedback to the driver that a collisionmitigation function is active and/or to help guide the drive to avoidthe collision. An audible warning can include audible tones or voicecommands for instructing the driver to avoid the collision or inform thedriver that an automated collision mitigation function is active. Atactile warning can include a steering wheel torque and/or vibration(i.e., haptic feedback) for helping the driver avoid the collision orinform the driver that an automated collision mitigation function isactive. Other subsystems or devices such as phones, tablets, vibratingseats may also be used. Changing frequencies of the vibration can beused to convey additional information about the probability of thecollision to the drive. Communication between the driver and vehicle canbe implemented using various modes of communication such as, forexample, vehicle audio system, park aid speakers, text display,navigation system, reverse camera system, massaging seats activation,joystick input, steering wheel input, mirror display, mobile phone,mobile computing device and/or mobile gaming device.

Referring now to FIG. 2, a preferred embodiment of the trailer back-upsteering input apparatus 125 discussed in reference to FIG. 1A is shown.A rotatable control element in the form of a knob 170 is coupled to amovement sensing device 175. The knob 170 is biased (e.g., by a springreturn) to an at-rest position P(AR) between opposing rotational rangesof motion R(R), R(L). A first one of the opposing rotational ranges ofmotion R(R) is substantially equal to a second one of the opposingrotational ranges of motion R(L), R(R). To provide a tactile indicationof an amount of rotation of the knob 170, a force that biases the knob170 toward the at-rest position P(AR) can increase (e.g., non-linearly)as a function of the amount of rotation of the knob 170 with respect tothe at-rest position P(AR). Additionally, the knob 170 can be configuredwith position indicating detents such that the driver can positivelyfeel the at-rest position P(AR) and feel the ends of the opposingrotational ranges of motion R(L), R(R) approaching (e.g., soft endstops).

The movement sensing device 175 is configured for sensing movement ofthe knob 170 and outputting a corresponding signal (i.e., movementsensing device signal) to the trailer assist back-up input apparatus 125shown in FIG. 1A. The movement sensing device signal is generated as afunction of an amount of rotation of the knob 170 with respect to theat-rest position P(AR), a rate movement of the knob 170, and/or adirection of movement of the knob with respect to the at-rest positionP(AR). As will be discussed below in greater detail, the at-restposition P(AR) of the knob 170 corresponds to a movement sensing devicesignal indicating that the vehicle 100 should be steered such that thetrailer 100 is backed along a substantially straight path as defined bya centerline longitudinal axis of the trailer 110 when the knob 170 wasreturned to the at-rest position P(AR) and a maximum clockwise andanti-clockwise position of the knob 170 (i.e., limits of the opposingrotational ranges of motion R(R), R(L)) each corresponds to a respectivemovement sensing device signal indicating a tightest radius of curvature(i.e., most acute trajectory) of a path of travel of the trailer 110that is possible without the corresponding vehicle steering informationcausing a jack-knife condition. In this regard, the at-rest positionP(AR) is a zero curvature commanding position with respect to theopposing rotational ranges of motion R(R), R(L). It is disclosed hereinthat a ratio of a commanded curvature of a path of a trailer (e.g.,radius of a trailer trajectory) and a corresponding amount of rotationof the knob can vary (e.g., non-linearly) over each one of the opposingrotational ranges of motion R(L), R(R) of the knob 170. It is alsodisclosed therein that the ratio can be a function of vehicle speed,trailer geometry, vehicle geometry, hitch geometry and/or trailer load.

Use of the knob 170 decouples trailer steering inputs from being made ata steering wheel of the vehicle 100. In use, as a driver of the vehicle100 backs the trailer 110, the driver can turn the knob 170 to dictate acurvature of a path of the trailer 110 to follow and returns the knob170 to the at-rest position P(AR) for causing the trailer 110 to bebacked along a straight line. Accordingly, in embodiments of trailerback-up assist systems where the steering wheel remains physicallycoupled to the steerable wheels of a vehicle during back-up of anattached trailer, a rotatable control element configured in accordancewith the inventive subject matter (e.g., the knob 170) provides a simpleand user-friendly means of allowing a driver of a vehicle to inputtrailer steering commands.

It is disclosed herein that a rotational control input device configuredin accordance with embodiments of the inventive subject matter (e.g.,the knob 170 and associated movement sensing device) can omit a meansfor being biased to an at-rest position between opposing rotationalranges of motion. Lack of such biasing allows a current rotationalposition of the rotational control input device to be maintained untilthe rotational control input device is manually moved to a differentposition. Preferably, but not necessarily, when such biasing is omitted,a means is provided for indicating that the rotational control inputdevice is positioned in a zero curvature commanding position (e.g., atthe same position as the at-rest position in embodiments where therotational control input device is biased). Examples of means forindicating that the rotational control input device is positioned in thezero curvature commanding position include, but are not limited to, adetent that the rotational control input device engages when in the zerocurvature commanding position, a visual marking indicating that therotational control input device is in the zero curvature commandingposition, an active vibratory signal indicating that the rotationalcontrol input device is in or approaching the zero curvature commandingposition, an audible message indicating that the rotational controlinput device is approaching the zero curvature commanding position, andthe like.

It is also disclosed herein that embodiments of the inventive subjectmatter can be configured with a control input device that is notrotational (i.e., a non-rotational control input device). Similar to arotational control input device configured in accordance withembodiments of the inventive subject matter (e.g., the knob 170 andassociated movement sensing device), such a non-rotational control inputdevice is configured to selectively provide a signal causing a trailerto follow a path of travel segment that is substantially straight and toselectively provide a signal causing the trailer to follow a path oftravel segment that is substantially curved. Examples of such anon-rotational control input device include, but are not limited to, aplurality of depressible buttons (e.g., curve left, curve right, andtravel straight), a touch screen on which a driver traces or otherwiseinputs a curvature for path of travel commands, a button that istranslatable along an axis for allowing a driver to input path of travelcommands, and the like.

The trailer back-up steering input apparatus 125 can be configured toprovide various feedback information to a driver of the vehicle 100.Examples of situations that such feedback information can indicateinclude, but are not limited to, a status of the trailer back-up assistsystem 105 (e.g., active, in standby (e.g., when driving forward toreduce the trailer angle), faulted, inactive, etc), that a curvaturelimit has been reached (i.e., maximum commanded curvature of a path oftravel of the trailer 110), etc. To this end, the trailer back-upsteering input apparatus 125 can be configured to provide a tactilefeedback signal (e.g., a vibration through the knob 170) as a warning ifany one of a variety of conditions occur. Examples of such conditionsinclude, but are not limited to, the trailer 110 having jack-knifed, thetrailer back-up assist system 105 has had a failure, the trailer back-upassist system 105 or other system of the vehicle 100 has predicted acollision on the present path of travel of the trailer 110, the trailerback-up system 105 has restricted a commanded curvature of a trailer'spath of travel (e.g., due to excessive speed or acceleration of thevehicle 100), and the like. Still further, it is disclosed that thetrailer back-up steering input apparatus 125 can use illumination (e.g.,an LED 180) and/or an audible signal output (e.g., an audible outputdevice 185) to provide certain feedback information (e.g.,notification/warning of an unacceptable trailer back-up condition).

Referring now to FIGS. 2 and 3, an example of using the trailer back-upsteering input apparatus 125 for dictating a curvature of a path oftravel (POT) of a trailer (i.e., the trailer 110 shown in FIG. 1A) whilebacking up the trailer with a vehicle (i.e., the vehicle 100 in FIGS. 1and 2) is shown. In preparation of backing the trailer 110, the driverof the vehicle 100 drives the vehicle 100 forward along a pull-thru path(PTP) to position the vehicle 100 and trailer 110 at a first back-upposition B1. In the first back-up position B1, the vehicle 100 andtrailer 110 are longitudinally aligned with each other such that alongitudinal centerline axis L1 of the vehicle 100 is aligned with(e.g., parallel with or coincidental with) a longitudinal centerlineaxis L2 of the trailer 110. It is disclosed herein that such alignmentof the longitudinal axes L1, L2 at the onset of an instance of trailerback-up functionality is not a requirement for operability of a trailerback-up assist system configured in accordance with the inventivesubject matter.

After activating the trailer back-up assist system 105 (e.g., before,after, or during the pull-thru sequence), the driver begins to back thetrailer 110 by reversing the vehicle 100 from the first back-up positionB1. So long as the knob 170 of the trailer back-up steering inputapparatus 125 remains in the at-rest position P(AR), the trailer back-upassist system 105 will steer the vehicle 100 as necessary for causingthe trailer 110 to be backed along a substantially straight path oftravel as defined by the longitudinal centerline axis L2 of the trailer110 at the time when backing of the trailer 110 began. When the trailerreaches the second back-up position B2, the driver rotates the knob 170to command the trailer 110 to be steered to the right (i.e., a knobposition R(R)). Accordingly, the trailer back-up assist system 105 willsteer the vehicle 100 for causing the trailer 110 to be steered to theright as a function of an amount of rotation of the knob 170 withrespect to the at-rest position P(AR), a rate movement of the knob 170,and/or a direction of movement of the knob 170 with respect to theat-rest position P(AR). Similarly, the trailer 110 can be commanded tosteer to the left by rotating the knob 170 to the left. When the trailerreaches back-up position B3, the driver allows the knob 170 to return tothe at-rest position P(AR) thereby causing the trailer back-up assistsystem 105 to steer the vehicle 100 as necessary for causing the trailer110 to be backed along a substantially straight path of travel asdefined by the longitudinal centerline axis L2 of the trailer 110 at thetime when the knob 170 was returned to the at-rest position P(AR).Thereafter, the trailer back-up assist system 105 steers the vehicle 100as necessary for causing the trailer 110 to be backed along thissubstantially straight path to the fourth back-up position B4. In thisregard, arcuate (e.g., curved) portions of a path of travel POT of thetrailer 110 are dictated by rotation of the knob 170 and straightportions of the path of travel POT are dictated by an orientation of thecenterline longitudinal axis L2 of the trailer when the knob 170 isin/returned to the at-rest position P(AR).

FIG. 4 shows a method 200 for implementing trailer back-up assistfunctionality in accordance with an embodiment of the inventive subjectmatter. In a preferred embodiment, the method 200 for implementingtrailer back-up assist functionality can be carried out using thetrailer back-up assist architecture discussed above in reference to thevehicle 100 and trailer 110 of FIG. 1A. Accordingly, trailer steeringinformation is provided through use of a rotational control input device(e.g., the knob 170 discussed in reference to FIG. 2).

An operation 202 is performed for receiving a trailer back-up assistrequest. Examples of receiving the trailer back-up assist requestinclude activating the trailer back-up assist system and providingconfirmation that the vehicle and trailer are ready to be backed. Afterreceiving a trailer back-up assist request (i.e., while the vehicle isbeing reversed), an operation 204 is performed for receiving a trailerback-up information signal. Examples of information carried by thetrailer back-up information signal include, but is not limited to,information from the trailer back-up steering input apparatus 125,information from the hitch angle detecting apparatus 130, informationfrom the power-steering assist control module 135, information from thebrake system control module 145, and information from the powertraincontrol module 150. It is disclosed herein that information from thetrailer back-up steering input apparatus 125 preferably includes trailerpath curvature information characterizing a desired curvature for thepath of travel of the trailer, such as provided by the trailer back-upsteering input apparatus 125 discussed above in reference to FIGS. 1 and2. In this manner, the operation 204 for receiving the trailer back-upinformation signal can include receiving trailer path curvatureinformation characterizing the desired curvature for the path of travelof the trailer.

If the trailer back-up information signal indicates that a change incurvature of the trailer's path of travel is requested (i.e., commandedvia the knob 170), an operation 206 is performed for determining vehiclesteering information for providing the requested change in curvature ofthe trailer's path of travel. Otherwise, an operation 208 is performedfor determining vehicle steering information for maintaining a currentstraight-line heading of the trailer (i.e., as defined by thelongitudinal centerline axis of the trailer). Thereafter, an operation210 is performed for providing the vehicle steering information to apower-steering assist system of the vehicle, followed by an operation212 being performed for determining the trailer back-up assist status.If it is determined that trailer back-up is complete, an operation 214is performed for ending the current trailer back-up assist instance.Otherwise the method 200 returns to the operation 204 for receivingtrailer back-up information. Preferably, the operation for receiving thetrailer back-up information signal, determining the vehicle steeringinformation, providing the vehicle steering information, and determiningthe trailer back-up assist status are performed in a monitoring fashion(e.g., at a high rate of speed of a digital data processing device).Accordingly, unless it is determined that reversing of the vehicle forbacking the trailer is completed (e.g., due to the vehicle having beensuccessfully backed to a desired location during a trailer back-upassist instance, the vehicle having to be pulled forward to beginanother trailer back-up assist instance, etc), the method 200 willcontinually be performing the operations for receiving the trailerback-up information signal, determining the vehicle steeringinformation, providing the vehicle steering information, and determiningthe trailer back-up assist status.

It is disclosed herein that the operation 206 for determining vehiclesteering information for providing the requested change in curvature ofthe trailer's path of travel preferably includes determining vehiclesteering information as a function of trailer path curvature informationcontained within the trailer back-up information signal. As will bediscussed below in greater detail, determining vehicle steeringinformation can be accomplished through a low order kinematic modeldefined by the vehicle and the trailer. Through such a model, arelationship between the trailer path curvature and commanded steeringangles of steered wheels of the vehicle can be generated for determiningsteering angle changes of the steered wheels for achieving a specifiedtrailer path curvature. In this manner, the operation 206 fordetermining vehicle steering information can be configured forgenerating information necessary for providing trailer path curvaturecontrol in accordance with the inventive subject matter.

In some embodiments of the inventive subject matter, the operation 210for providing the vehicle steering information to the power-steeringassist system of the vehicle causes the steering system to generate acorresponding steering command as a function of the vehicle steeringinformation. The steering command is interpretable by the steeringsystem and is configured for causing the steering system to move steeredwheels of the steering system for achieving a steered angle as specifiedby the vehicle steering information. Alternatively, the steering commandcan be generated by a controller, module or computer external to thesteering system (e.g., a trailer back-up assist control module) and beprovided to the steering system.

In parallel with performing the operations for receiving the trailerback-up information signal, determining the vehicle steeringinformation, providing the vehicle steering information, and determiningthe trailer back-up assist status, the method 200 performs an operation216 for monitoring the trailer back-up information for determining if anunacceptable trailer back-up condition exists. Examples of suchmonitoring include, but are not limited to assessing a hitch angle todetermine if a hitch angle threshold is exceeded, assessing a back-upspeed to determine if a back-up speed threshold is exceeded, assessingvehicle steering angle to determining if a vehicle steering anglethreshold is exceeded, assessing other operating parameters (e.g.,vehicle longitudinal acceleration, throttle pedal demand rate and hitchangle rate) for determining if a respective threshold value is exceeded,and the like. Back-up speed can be determining from wheel speedinformation obtained from one or more wheel speed sensors of thevehicle. If it is determined that an unacceptable trailer back-upcondition exists, an operation 218 is performed for causing the currentpath of travel of the trailer to be inhibited (e.g., stopping motion ofthe vehicle), followed by the operation 214 being performed for endingthe current trailer back-up assist instance. It is disclosed herein thatprior to and/or in conjunction with causing the current trailer path tobe inhibited, one or more actions (e.g., operations) can be implementedfor providing the driver with feedback (e.g., a warning) that such anunacceptable trailer angle condition is impending or approaching. In oneexample, if such feedback results in the unacceptable trailer anglecondition being remedied prior to achieving a critical condition, themethod can continue with providing trailer back-up assist functionalityin accordance with operations 204-212. Otherwise, the method can proceedto operation 214 for ending the current trailer back-up assist instance.In conjunction with performing the operation 214 for ending the currenttrailer back-up assist instance, an operation can be performed forcontrolling movement of the vehicle to correct or limit a jack-knifecondition (e.g., steering the vehicle, decelerating the vehicle,limiting magnitude and/or rate of driver requested trailer curvatureinput, and/or the like to preclude the hitch angle from being exceeded).

Turning now to a discussion of a kinematic model used to calculate arelationship between a curvature of a path of travel of a trailer andthe steering angle of a vehicle towing the trailer, a low orderkinematic model can be desirable for a trailer back-up assist systemconfigured in accordance with some embodiments of the inventive subjectmatter. To achieve such a low order kinematic model, certain assumptionsare made with regard to parameters associated with the vehicle/trailersystem. Examples of such assumptions include, but are not limited to,the trailer being backed by the vehicle at a relatively low speed,wheels of the vehicle and the trailer having negligible (e.g., no) slip,tires of the vehicle, vehicle lateral compliance, and the trailer havingnegligible (e.g., no) deformation, actuator dynamics of the vehiclebeing negligible, the vehicle and the trailer exhibiting negligible(e.g., no) roll or pitch motions.

As shown in FIG. 5, for a system defined by a vehicle 302 and a trailer304, the kinematic model 300 is based on various parameters associatedwith the vehicle 302 and the trailer 304. These kinematic modelparameters include:

δ: steering angle at steered front wheels 306 of the vehicle 302;

α: yaw angle of the vehicle 302;

β: yaw angle of the trailer 304;

γ: hitch angle (γ=β−α);

W: wheel base of the vehicle 302;

L: length between hitch point 308 and rear axle 310 of the vehicle 302;

D: length between hitch point 308 and axle 312 of the trailer 304; and

r₂: curvature radius for the trailer 304.

The kinematic model 300 of FIG. 5 reveals a relationship between trailerpath radius of curvature r₂ at the midpoint 314 of an axle 306 of thetrailer 304, steering angle δ of the steered wheels 306 of the vehicle302, and the hitch angle γ. As shown in the equation below, thisrelationship can be expressed to provide the trailer path curvature κ₂such that, if γ is given, the trailer path curvature κ₂ can becontrolled based on regulating the steering angle δ (where β(·) istrailer yaw rate and η(·) is trailer velocity).

$\kappa_{2} = {\frac{1}{r_{2}} = {\frac{\overset{.}{\beta}}{\overset{.}{\eta}} = \frac{{\left( {W + \frac{{KV}^{2}}{g}} \right)\sin \; \gamma} + {L\; \cos \; \gamma \; \tan \; \delta}}{D\left( {{\left( {W + \frac{{KV}^{2}}{g}} \right)\cos \; \gamma} - {L\; \sin \; \gamma \; \tan \; \delta}} \right)}}}$

Or, this relationship can be expressed to provide the steering angle δas a function of trailer path curvature κ2 and hitch angle γ.

$\delta = {{\tan^{- 1}\left( \frac{\left( {W + \frac{{KV}^{2}}{g}} \right)\left\lbrack {{\kappa_{2}D\; \cos \; \gamma} - {\sin \; \gamma}} \right\rbrack}{{{DL}\; \kappa_{2}\sin \; \gamma} + {L\; \cos \; \gamma}} \right)} = {F\left( {\gamma,\kappa_{2},K} \right)}}$

Accordingly, for a particular vehicle and trailer combination, certainkinematic model parameters (e.g., D, W and L) are constant and assumedknown. V is the vehicle longitudinal speed and g is the acceleration dueto gravity. K is a speed dependent parameter which when set to zeromakes the calculation of steering angle independent of vehicle speed.For example, vehicle-specific kinematic model parameters can bepredefined in an electronic control system of a vehicle andtrailer-specific kinematic model parameters can be inputted by a driverof the vehicle. Trailer path curvature κ₂ is determined from the driverinput via a trailer back-up steering input apparatus. Through the use ofthe equation for providing steering angle, a corresponding steeringcommand can be generated for controlling a steering system (e.g., anactuator thereof) of the vehicle.

FIG. 6 shows an example of a trailer path curvature function plot 400for a rotary-type trailer back-up steering input apparatus (e.g., thetrailer back-up steering input apparatus 125 discussed above inreference to FIGS. 1 and 2). A value representing trailer path curvature(e.g., trailer path curvature κ2) is provided as an output signal fromthe rotary-type trailer back-up steering input apparatus as a functionof user input movement. In this example, a curve 402 specifying trailerpath curvature relative to user input (e.g., amount of rotation) at arotary input device (e.g., a knob) is defined by a cubic function.However, a skilled person will appreciate that embodiments of theinventive subject matter are not limited to any particular functionbetween a magnitude and/or rate of input at a trailer back-up steeringinput apparatus (e.g., knob rotation) and a resulting trailer pathcurvature value.

Referring to FIG. 5, in preferred embodiments of the inventive subjectmatter, it is desirable to limit the potential for the vehicle 302 andthe trailer 304 to attain a jack-knife angle (i.e., the vehicle/trailersystem achieving a jack-knife condition). A jack-knife angle γ(j) refersto a hitch angle γ that cannot be overcome by the maximum steering inputfor a vehicle, when the vehicle is reversing, such as, for example, thesteered front wheels 306 of the vehicle 302 being moved to a maximumsteered angle δ at a maximum rate of steering angle change. Thejack-knife angle γ(j) is a function of a maximum wheel angle for thesteered wheel 306 of the vehicle 302, the wheel base W of the vehicle302, the distance L between hitch point 308 and the rear axle 310 of thevehicle 302, and the length D between the hitch point 308 and the axle312 of the trailer 304. When the hitch angle γ for the vehicle 302 andthe trailer 304 achieves or exceeds the jack-knife angle γ(j), thevehicle 302 must be pulled forward to reduce the hitch angle γ. Thus,for limiting the potential for a vehicle/trailer system attaining ajack-knife angle, it is preferable to control the yaw angle of thetrailer while keeping the hitch angle of the vehicle/trailer systemrelatively small. Referring to FIGS. 5 and 7, a steering angle limit forthe steered front wheels 306 requires that the hitch angle γ cannotexceed the jack-knife angle γ(j), which is also referred to as acritical hitch angle. Thus, under the limitation that the hitch angleγcannot exceed the jack-knife angle γ(j), the jack-knife angle γ(j) isthe hitch angle γ that maintains a circular motion for thevehicle/trailer system when the steered wheels 306 are at a maximumsteering angle δ(max). The steering angle for circular motion with hitchangle is defined by the following equation.

${\tan \; \delta_{\max}} = \frac{W\; \sin \; \gamma_{\max}}{D + {L\; \cos \; \gamma_{\max}}}$

Solving the above equation for hitch angle allows jack-knife angle γ(j)to be determined. This solution, which is shown in the followingequation, can be used in implementing trailer back-up assistfunctionality in accordance with the inventive subject matter formonitoring hitch angle in relation to jack-knife angle.

${{\cos \; \overset{\_}{\gamma}} = \frac{{- b} \pm \sqrt{b^{2} - {4\; {ac}}}}{2\; a}},$

where,

a=L ² tan² δ(max)+W ²;

b=2LD tan² δ(max); and

c=D ² tan² δ(max)−W ².

In certain instances of backing a trailer, a jack-knife enablingcondition can arise based on current operating parameters of a vehiclein combination with a corresponding hitch angle. This condition can beindicated when one or more specified vehicle operating thresholds aremet while a particular hitch angle is present. For example, although theparticular hitch angle is not currently at the jack-knife angle for thevehicle and attached trailer, certain vehicle operating parameters canlead to a rapid (e.g., uncontrolled) transition of the hitch angle tothe jack-knife angle for a current commanded trailer path curvatureand/or can reduce an ability to steer the trailer away from thejack-knife angle. One reason for a jack-knife enabling condition is thattrailer curvature control mechanisms (e.g., those in accordance with theinventive subject matter) generally calculate steering commands at aninstantaneous point in time during backing of a trailer. However, thesecalculations will typically not account for lag in the steering controlsystem of the vehicle (e.g., lag in a steering EPAS controller). Anotherreason for the jack-knife enabling condition is that trailer curvaturecontrol mechanisms generally exhibit reduced steering sensitivity and/oreffectiveness when the vehicle is at relatively high speeds and/or whenundergoing relatively high acceleration.

FIG. 8 shows a method 500 for implementing jack-knife countermeasuresfunctionality in accordance with an embodiment of the inventive subjectmatter for a vehicle and attached trailer. Trailer back-up assistfunctionality in accordance with the inventive subject matter caninclude jack-knife countermeasures functionality. Alternatively,jack-knife countermeasures functionality in accordance with anembodiment of the inventive subject matter can be implemented separatelyfrom other aspects of trailer back-up assist functionality.

The method 500 begins when operation 502 is performed for receivingjack-knife determining information characterizing a jack-knife enablingcondition of the vehicle-trailer combination at a particular point intime (e.g., at the point in time when the jack-knife determininginformation was sampled). Examples of the jack-knife determininginformation includes, but are not limited to, information characterizinga hitch angle, information characterizing a vehicle accelerator pedaltransient state, information characterizing a speed of the vehicle,information characterizing longitudinal acceleration of the vehicle,information characterizing a brake torque being applied by a brakesystem of the vehicle, information characterizing a powertrain torquebeing applied to driven wheels of the vehicle, and informationcharacterizing the magnitude and rate of driver requested trailercurvature. The operation 502 for receiving jack-knife determininginformation can be the first operation in a sampling process wherejack-knife determining information is sampled upon initiation of aninstance of implementing jack-knife countermeasures functionality. Inthis regard, jack-knife determining information would be continuallymonitored such as, for example, by a electronic control unit (ECU) thatcarries out trailer back-up assist (TBA) functionality. As discussedabove in reference to FIG. 5, a kinematic model representation of thevehicle and the trailer can be used to determine a jack-knife angle forthe vehicle-trailer combination. However, the inventive subject matteris not unnecessarily limited to any specific approach for determiningthe jack-knife angle.

After receiving the jack-knife determining information, an operation 504is performed for assessing the jack-knife determining information fordetermining if the vehicle-trailer combination attained the jack-knifeenabling condition at the particular point in time. The objective of theoperation 504 for assessing the jack-knife determining information isdetermining if a jack-knife enabling condition has been attained at thepoint in time defined by the jack-knife determining information. If itis determined that a jack-knife enabling condition is not present at theparticular point in time, the method 500 returns to the operation 502for receiving another instance of the jack-knife determininginformation. If it is determined that a jack-knife enabling condition ispresent at the particular point in time, an operation 506 is performedfor determining an applicable counter-measure or counter-measures toimplement. Accordingly, in some embodiments of the inventive subjectmatter, an applicable counter-measure will be selected dependent upon aparameter identified as being a key influencer of the jack-knifeenabling condition. However, in other embodiments, an applicablecounter-measure will be selected as being most able to readily alleviatethe jack-knife enabling condition. In still other embodiment, apre-defined counter-measure or pre-defined set of counter-measures maybe the applicable counter-measure(s).

The objective of a counter-measure in the context of the inventivesubject matter (i.e., a jack-knife reduction countermeasure) is toalleviate a jack-knife enabling condition. To this end, such acounter-measure can be configured to alleviate the jack-knife enablingcondition using a variety of different strategies. In a vehicle speedsensitive counter-measure strategy, actions taken for alleviating thejack-knife enabling condition can include overriding and/or limitingdriver requested trailer radius of curvature (e.g., being requested viaa trailer back-up steering input apparatus configured in accordance withthe inventive subject matter) as a function of vehicle speed (e.g., viaa look-up table correlating radius of curvature limits to vehicle speedas shown in FIG. 6). In a counter-measure strategy where trailercurvature requests are limited as a function of speed and drivercurvature command transient rates, actions taken for alleviating thejack-knife enabling condition can include rate limiting trailercurvature command transients as requested by a driver above apre-defined vehicle speed whereas, under the pre-defined vehicle speed,the as-requested trailer curvature are not rate limited. In a torquelimiting counter-measure strategy, actions taken for alleviating thejack-knife enabling condition can include application of full availablepowertrain torque being inhibited when the jack-knife enabling conditionis present while the vehicle is above a pre-defined speed andapplication of full available powertrain torque being allowed when thevehicle speed is reduced below the pre-defined speed while in the torqueinhibiting mode. As opposed to a fixed pre-defined speed, the torquelimiting counter-measure strategy can utilize a speed threshold that isa function of hitch angle (i.e., speed threshold inversely proportionalto hitch angle acuteness). In a driver accelerator pedal transientdetection counter-measure strategy, actions taken for alleviating thejack-knife enabling condition can include overriding and/or limitingdriver requested trailer radius of curvature as a function of transientaccelerator pedal requests (e.g., requested trailer radius of curvaturelimited when a large accelerator pedal transient is detected). In ahitch angle rate sensitive counter-measure strategy, actions taken foralleviating the jack-knife enabling condition can include using hitchangle rate in a predefined or calculated mapping with current hitchangle position to limit driver requested trailer radius of curvature.Accordingly, in view of the disclosures made herein, a skilled personwill appreciate that embodiments of the inventive subject matter are notunnecessarily limited to a counter-measure strategy of any particularconfiguration.

As disclosed above, implementation of trailer back-up assistfunctionality in accordance with the inventive subject matter canutilize a kinematic model for determining steering control information,jack-knife enabling conditions, and jack-knife angle. Such a kinematicmodel has many parameters than can influence trailer curvature controleffectiveness. Examples of these parameters include, but are not limitedto, the vehicle wheelbase, understeer gradient gain, vehicle trackwidth, maximum steer angle at the vehicle front wheels, minimum turningradius of vehicle, maximum steering rate able to be commanded by thesteering system, hitch ball to trailer axle length, and vehicle rearaxle to hitch ball length. Sensitivity analysis for a given kinematicmodel can be used to provide an understanding (e.g., sensitivity) of therelationships between such parameters, thereby providing informationnecessary for improving curvature control performance and for reducingthe potential for jack-knife enabling conditions. For example, throughan understanding of the sensitivity of the parameters of a kinematicmodel, scaling factors can be used with speed dependent jack-knifecounter-measures to reduce jack-knife potential (e.g., for specialapplications such as short wheelbase conditions).

Still referring to FIG. 8, after determining the applicablecountermeasure(s), an operation 508 is performed for implementing thechosen jack-knife countermeasure(s) and an operation 510 is performedfor initiating a jack-knife warning. As discussed above in regard tocounter-measure strategies, implementing the jack-knifecounter-measure(s) can include commanding a speed controlling system ofthe vehicle to transition to an altered state of operation in which aspeed of the vehicle is reduced, commanding the steering control systemof the vehicle to transition to an altered state of operation in which aradius of a curvature of a path of the trailer is increased, command thesteering control system of the vehicle to transition to an altered stateof operation in which an increase in the radius of the curvature of thepath of the trailer is inhibited, commanding a brake control system ofthe vehicle to apply brake torque to reduce vehicle speed/inhibitvehicle acceleration, and/or commanding a powertrain control system ofthe vehicle to inhibit full available powertrain torque from beingdelivered to driven wheels of the vehicle until another jack-knifeenabling parameter (e.g., vehicle speed) is below a defined threshold.In certain embodiments of the inventive subject matter, the jack-knifewarning is provided to the driver using at least one vehicle controlsystem through which the jack-knife counter-measure is implemented.Speed reduction can be accomplished by any number of means such as, forexample, limiting throttle inputs (e.g., via a terrain managementfeature) and/or transitioning a transmission to a reverse low gear ifthe vehicle is equipped with a multi-range reverse gear transmission.Examples of such system-specific warning approach include, but are notlimited to, providing a warning through an accelerator pedal of thevehicle (e.g., via haptic feedback) if the counter-measure includeslimiting speed of the vehicle and/or providing a warning through aninput element (e.g., knob) of a trailer back-up steering input apparatusof the vehicle (e.g., via haptic feedback if the counter-measureincludes limiting driver requested trailer radius of curvature), throughhaptic seat vibration warning, through a visual warning (e.g., a througha visual display apparatus of the towing vehicle) and/or through aaudible warnings (e.g., through an audio output apparatus of the towingvehicle), or the like. One embodiment of utilizing warnings relating tovehicle speed as it related to onset or presence of a jack-knifeenabling condition includes implementation of a dual stage warning. Forexample, when a backing speed of the vehicle increases sufficiently forcausing a speed of the vehicle to reach a lower (i.e., first) speedthreshold during backing of the trailer, a driver of the vehicle wouldbe provided with a first warning indication (e.g., via haptic, audible,and/or visual means as implemented by the trailer back-up assist system)for informing the driver that there is the need to reduce the speed ofthe vehicle to alleviate or prelude the jack-knife enabling condition.If the driver does not correspondingly respond by causing a speed of thevehicle to be reduced (or not to further increase) and the vehiclecontinues to gain speed such that it passes a higher (i.e., a second)speed threshold, the driver of the vehicle would be provided with asecond warning indication (e.g., a more severed haptic, audible, and/orvisual means as implemented by the trailer back-up assist system) forinforming the driver that there is an immediate need to reduce the speedof the vehicle to alleviate or prelude the jack-knife enablingcondition. The first and/or the second speed indication warnings can beimplemented in conjunction with a respective speed limitingcounter-measure measures (e.g., the trailer back-up assist systemcausing activation of a brake system of the vehicle and/or deducing athrottle position of the vehicle).

Referring now to instructions processible by a data processing device,it will be understood from the disclosures made herein that methods,processes and/or operations adapted for carrying out trailer back-upassist functionality as disclosed herein are tangibly embodied bynon-transitory computer readable medium having instructions thereon thatare configured for carrying out such functionality. The instructions aretangibly embodied for carrying out the method 100 and/or the method 200disclosed and discussed above and can be further configured for limitingthe potential for a jack-knife condition such as, for example, bymonitoring jack-knife angle through use of the equations discussed inreference to FIGS. 5 and 7 and/or by implementing jack-knifecountermeasures functionality discussed above in reference to FIG. 8.

The instructions may be accessible by one or more data processingdevices from a memory apparatus (e.g. RAM, ROM, virtual memory, harddrive memory, etc), from an apparatus readable by a drive unit of a dataprocessing system (e.g., a diskette, a compact disk, a tape cartridge,etc) or both. Accordingly, embodiments of computer readable medium inaccordance with the inventive subject matter include a compact disk, ahard drive, RAM or other type of storage apparatus that has imagedthereon a computer program (i.e., instructions) configured for carryingout trailer back-up assist functionality in accordance with theinventive subject matter.

In a preferred embodiment of the inventive subject matter, a trailerback-up assist control module (e.g., the trailer back-up assist controlmodule 120 discussed above in reference to FIG. 1A) comprises such adata processing device, such a non-transitory computer readable medium,and such instructions on the computer readable medium for carrying outtrailer back-up assist functionality (e.g., in accordance with themethod 200 discussed above in reference to FIG. 2 and/or the method 500discussed above in reference to FIG. 8). To this end, the trailerback-up assist control module can comprise various signal interfaces forreceiving and outputting signals. For example, a jack-knife enablingcondition detector can include a device providing hitch angleinformation and hitch angle calculating logic of the trailer back-upassist control module. A trailer back-up assist control module in thecontext of the inventive subject matter can be any control module of anelectronic control system that provides for trailer back-up assistcontrol functionality in accordance with the inventive subject matter.Furthermore, it is disclosed herein that such a control functionalitycan be implemented within a standalone control module (physically andlogically) or can be implemented logically within two or more separatebut interconnected control modules (e.g., of an electronic controlsystem of a vehicle) In one example, trailer back-up assist controlmodule in accordance with the inventive subject matter is implementedwithin a standalone controller unit that provides only trailer back-upassist functionality. In another example, trailer back-up assistfunctionality in accordance with the inventive subject matter isimplemented within a standalone controller unit of an electronic controlsystem of a vehicle that provides trailer back-up assist functionalityas well as one or more other types of system control functionality of avehicle (e.g., anti-lock brake system functionality, steering powerassist functionality, etc). In still another example, trailer back-upassist functionality in accordance with the inventive subject matter isimplemented logically in a distributed manner whereby a plurality ofcontrol units, control modules, computers, or the like (e.g., anelectronic control system) jointly carry out operations for providingsuch trailer back-up assist functionality.

In the preceding detailed description, reference has been made to theaccompanying drawings that form a part hereof, and in which are shown byway of illustration specific embodiments in which the inventive subjectmatter may be practiced. These embodiments, and certain variantsthereof, have been described in sufficient detail to enable thoseskilled in the art to practice embodiments of the inventive subjectmatter. It is to be understood that other suitable embodiments may beutilized and that logical, mechanical, chemical and electrical changesmay be made without departing from the spirit or scope of such inventivedisclosures. To avoid unnecessary detail, the description omits certaininformation known to those skilled in the art. The preceding detaileddescription is, therefore, not intended to be limited to the specificforms set forth herein, but on the contrary, it is intended to coversuch alternatives, modifications, and equivalents, as can be reasonablyincluded within the spirit and scope of the appended claims.

1. A method for assisting a driver to back-up a vehicle-trailercombination, the vehicle having a data processing device, comprising thesteps of: assessing a proximity of an object adjacent to thevehicle-trailer combination during backing-up of the trailer toward atargeted location; determining whether a path of travel of thevehicle-trailer combination needs to be altered to avoid colliding withthe adjacent object; and implementing a path correction action to alterthe path of travel.
 2. The method of claim 1 wherein the step ofassessing further comprises assessing at least one of: informationcharacterizing engine torque requests of the vehicle; informationcharacterizing longitudinal acceleration of the vehicle; informationcharacterizing steering wheel angle of the vehicle; informationcharacterizing path of travel curvature for the trailer; and informationcharacterizing a hitch angle between the vehicle and the trailer.
 3. Themethod of claim 1 wherein the step of assessing further comprisesassessing information from at least one of a proximity informationcapturing device mounted on the trailer and a proximity informationcapturing device mounted on the vehicle.
 4. The method of claim 3wherein assessing in information further comprises assessing informationfrom a proximity information capturing device mounted on the trailer andfrom a proximity information capturing device mounted on the vehicle. 5.The method of claim 4 wherein the step of assessing further comprisesassessing at least one of: information characterizing engine torquerequests of the vehicle; information characterizing longitudinalacceleration of the vehicle; information characterizing steering wheelangle of the vehicle; information characterizing path of travelcurvature for the trailer; and information characterizing a hitch anglebetween the vehicle and the trailer.
 6. The method of claim 1 whereinthe step of assessing further comprises assessing information from atleast one of an ultrasonic sensor and a camera.
 7. The method of claim 1wherein the step of implementing a path correction action furthercomprises issuing at least one of: a command to alter a speed controlcondition of the vehicle-trailer combination; a command to alter asteering control condition of the vehicle-trailer combination; and acommand to alter a trailer curvature control condition of thevehicle-trailer combination.
 8. The method of claim 7 wherein the stepof assessing further comprises assessing at least one of: informationcharacterizing engine torque requests of the vehicle; informationcharacterizing longitudinal acceleration of the vehicle; informationcharacterizing steering wheel angle of the vehicle; informationcharacterizing path of travel curvature for the trailer; and informationcharacterizing a hitch angle between the vehicle and the trailer.
 9. Themethod of claim 8 wherein the step of assessing further comprisesassessing information from at least one of a proximity informationcapturing device mounted on the trailer and a proximity informationcapturing device mounted on the vehicle.
 10. The method of claim 9wherein assessing information further comprises assessing informationfrom a proximity information capturing device mounted on the trailer andfrom a proximity information capturing device mounted on the vehicle.11. A trailer back-up assist apparatus, comprising: an obstacle sensingsystem outputting proximity information of an object adjacent to avehicle-trailer combination while the vehicle-trailer combination isbeing backed toward a targeted location; and a trailer back-up assistsystem coupled to the obstacle sensing system, wherein the trailerback-up assist system uses the proximity information to determine if apath of the vehicle-trailer combination needs to be altered to avoid acollision with the object and to alter the path of travel of thevehicle-trailer combination to avoid the collision with the object. 12.The trailer back-up assist apparatus of claim 11 wherein the obstaclesensing system includes at least one of a proximity informationcapturing device mounted on the trailer and a proximity informationcapturing device mounted on the vehicle.
 13. The trailer back-up assistapparatus of claim 11 wherein the obstacle sensing system includes atleast one of a camera mounted on the vehicle and an ultrasonic sensormounted on the vehicle.
 14. The trailer back-up assist apparatus ofclaim 11 wherein the trailer back-up assist system uses at least one of:information characterizing engine torque requests of the vehicle;information characterizing longitudinal acceleration of the vehicle;information characterizing steering wheel angle of the vehicle;information characterizing path of travel curvature for the trailer; andinformation characterizing a hitch angle between the vehicle and thetrailer.
 15. The trailer back-up assist apparatus of claim 11 whereinthe trailer back-up assist system implements a path correction action byissuing at least one of: a command to alter a speed control condition ofthe vehicle-trailer combination; a command to alter a steering controlcondition of the vehicle-trailer combination; and a command to alter atrailer curvature control condition of the vehicle-trailer combination.16. The trailer back-up assist apparatus of claim 15 wherein theobstacle sensing system includes at least one of a proximity informationcapturing device mounted on the trailer and a proximity informationcapturing device mounted on the vehicle.
 17. The trailer back-up assistapparatus of claim 16 wherein the trailer back-up assist system uses atleast one of: information characterizing engine torque requests of thevehicle; information characterizing longitudinal acceleration of thevehicle; information characterizing steering wheel angle of the vehicle;information characterizing path of travel curvature for the trailer; andinformation characterizing a hitch angle between the vehicle and thetrailer 18-24. (canceled)
 25. A method for avoiding a collision betweenan object and a vehicle-trailer combination during backing of thetrailer along a path of travel toward a target location, comprising thesteps of: assessing proximity of the object to the vehicle-trailercombination during backing-up of the trailer; and altering the path oftravel of the vehicle-trailer combination based on the proximity of theobject to avoid the collision with the object.
 26. The method of claim25, wherein the step of altering the path of travel further comprisesthe step of implementing a path correction action to the vehicle-trailercombination.
 27. The method of claim 25, wherein the step of assessingfurther comprises assessing at least one of: a signal representative ofengine torque requests of the vehicle; a signal representative of alongitudinal acceleration of the vehicle; information representative ofa path of travel curvature of the trailer; and a signal representativeof a hitch angle between the vehicle and the trailer.
 28. The method ofclaim 25, wherein the step of assessing further comprises assessinginformation received from at least one of a proximity informationcapturing device mounted on the trailer and a proximity informationcapturing device mounted on the vehicle.
 29. The method of claim 28,further comprises assessing information received from a proximityinformation capturing device mounted on the vehicle and a proximityinformation capturing device mounted on the vehicle.
 30. The method ofclaim 29, wherein the step of assessing further comprises assessing atleast one of: a signal representative of engine torque requests of thevehicle; a signal representative of a longitudinal acceleration of thevehicle; information representative of a path of travel curvature of thetrailer; and a signal representative of a hitch angle between thevehicle and the trailer.
 31. The method of claim 25, wherein the step ofassessing further comprises assessing information from at least one ofan ultrasonic sensor and a camera.
 32. The method of claim 26, whereinthe step of implementing a path correction action further compriseissuing at least one of: a command to alter a speed control condition ofthe vehicle-trailer combination; a command to alter a steering controlcondition of the vehicle-trailer combination; and a command to alter atrailer curvature control condition of a vehicle-trailer combination.